Signs with multiple changeable sub-elements improve flexibility, hasten updates, and reduce expense over signs with a single panel. U.S. Pat. No. 8,533,982 shows a sign formed from multiple panels installed on tracks. Each panel abuts other panels to display a larger combined image. Each panel displays a cellular portion of an array forming the larger image. Parts of the image can be quickly changed without changing the whole sign. For example one panel may show the price of a displayed food item at a restaurant. The price is changeable by replacing only that single panel, without changing other panels.